This development pertains to the art of fluid handling devices and more particularly to fluid fittings.
The development is particularly applicable to an elbow type fluid fitting and will be described with particular reference thereto. However, it will be appreciated by those skilled in the art that the invention has broader applications and may be used in other applications and environments.
Elbow type fluid fittings generally include a pair of fitting branches disposed at some angular relationship relative to each other for purposes of interconnecting adjacent ends of a pair of fluid conduit means at some desired angle. Typically, the fitting branches are disposed at substantially right angles to each other although in some instances, other angular relationships are advantageously utilized. Fluid passageways extend longitudinally of the branches and communicate with each other at their innermost ends. The outermost or terminal ends of the fitting branches include convenient means for effecting mechanical interconnections between the conduit means and elbow. Such connecting means include, but are not limited to, male and female pipe ends, tube fitting ends, weld fitting ends and the like. Certain types of elbow constructions require substantially more machining during manufacture thereof than do others. Typical of these are so-called forged fittings wherein a forged fitting blank is machined in a manner to at least include fluid passageways through the branches as well as the desired branch ends for installing the fitting in a fluid system. However, and in addition to the forged type of construction, such blanks may be die machined from stock, cast, sintered and/or molded. For some applications of elbow fittings, it is highly desired that the below branch passageways be precisely angularly disposed relative to each other. This is deemed to be particularly important when the fittings are to be used in precise installations such as gas chromatographs, nuclear reactors, medical apparatus, laboratory apparatus and the like. However, it has been noted over the years that the variation in this angularity falls within much broader ranges than the angularity experienced with respect to the axes of intersection of other types of fittings such as, for example, tees and crosses.
When machining fluid fittings of this general type, a chuck is employed for clampingly engaging the fitting to retain it in position during various machining operations. Such chucks have typically included opposed jaws constructed of hardened tool steel and configured to clamp the fitting blank in a manner which will not interfere with subsequent maching operations. When using such chucks, it is not possible to rigidly clamp an elbow type of fitting since there are only two ends or branches to begin with and one of these ends or branches will be in the process of being machined at any given time. Previously, chucks having hardened steel jaws were designed to engage each branch on opposite sides thereof adjacent the body of the fitting with the body itself being located in a receiving area of cavity in the chuck. To enhance blank stability, body engagement means penetrated the receiving area or cavity. These engagement means were selectively adjustable in the cavity to facilitate positive engagement with the body of the blank. Such chuck designs have not provided the degree of rigidity or stability required to cause the fitting to run true during machining.
To overcome the aforementioned problem, some prior clamping jaws have been molded to conform to the exterior conformation of the elbow fitting itself in an effort to provide increased support over the surfaces of the fitting. However, because of the nature of the molding operations, it is only possible to construct the jaws from a low temperature melting point, rather soft material in the nature of a pot metal. Because of its softness, this material wears easily and does not hold up well over prolonged periods of use. As a consequence, it is not possible to maintain the kind of rigidity necessary to assure optimum control over the angularity of the elbow branch passageways. Another disadvantage involved in the use of pot metal clamping jaws resides in the fact that a machine operator has to lightly "tap" the fitting blank with a hammer once it has been chucked in order to insure that it is properly seated within the chuck jaws. Such an operation is not conducive to automatic loading and necessarily results in additional man hours and machine time for producing each elbow type fitting. Moreover, and in order for the operator to "tap" the fitting, he must place his hands in close proximity with the machine which undesirably creates a potential safety hazard.
It has, therefore, been considered desirable in the industry to develop some arrangement which would overcome the aforenoted problems and others. The subject development provides an article and method which allow elbow type fluid fittings to be more accurately machined so that at least the fluid flow passageways will be more accurately positioned angularly of each other because of greater rigidity obtained in the clamping action. It also allows use of chucking systems and arrangements which more closely conform to those which are utilized for machining other types of fittings, and which facilitate automatic loading and machining for increasing production capabilities, and which are readily adapted to use for many elbow types and styles.